DOCSLIB.ORG

N O T I C E This Document Has Been Reproduced From

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
N O T I C E This Document Has Been Reproduced From N O T I C E THIS DOCUMENT HAS BEEN REPRODUCED FROM MICROFICHE. ALTHOUGH IT IS RECOGNIZED THAT CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED IN THE INTEREST OF MAKING AVAILABLE AS MUCH INFORMATION AS POSSIBLE NASA Technical Memorandum 80694 THE 1979 X-RAY OUTBURST OF CEN X-4 (NASA-Td-80694) THE 1979 X-RAY OUTBURST OF X180-26135 CEN X-4 (NASA) 25 p HC A02/11F A01 CSCL 03B Unclas G3/90 22947 L. J. Kaluzienski S. S. Holt J. H. Swank MAY 1980 National Aeronautics and Space Administration •'8n Goddard Space Flight Center Greenbelt, Maryland 20771 NA q 8;7 t p DEpr L- -._ . V THE 1979 X-RAY OUTBURST OF CEN X-4 L.J. Kaluzienski l , S.S. Holt, and J.H. Swank Laboratory for High Energy Astrophysics NASA/Goddard Space Flight Center Greenbelt, Maryland 20771 ABSTRACT In late spring 1979 the "classical" transient X-ray source Cen X-4 under- went its first major outburst since its initial discovery in 1969. We present X-ray observations of this event obtained with the Arie l 5 All-Sky Monitor. The flare light curve exhibits a double-peaked maximum at a level of ti 4 times the Crab nebula,and its duration and characteristic decay time scale are the shortest yet observed from the class of "soft" X-ray transients. We estimate a total X-ray output of ti 3 x 1043 ergs, a factor of ti 20 less than that of the 1969 outburst, In addition, evidence is found for a regular modulation of the flux during the decline phase at a period of 8.2 + 0.2 hours. The existing data are consistent with a source model involving episodic mass exchange from a late-type dwarf onto a neutron star companion in a relatively close binary system, Subject headings: stars: binaries - stars: individual - X-Rays: binaries - X-Rays: bursts 1 Now at NASA Headquarters, Washington, D.C. - 2 - I. INTRODUCTION An outburst from the long-dormant transient X-ray source Cen X-4 was deters-. in 1979 May with the All-Sky Monitor (ASM) on Ariel 5 (Kaluzienski and Molt 1979 b,O. The only other recorded X-ray outburst from this object was observed with the Vela 5 satellites in 1969 July, when the source reached a peak intensity of ti 5 x 10 -7 erg cm-2 s -1 (3-12 keV) and remained bright (S >ml Smax) for more than two months (Evans, Belian, and Conner 1970). The absence of the source in the HEAO-A2 sky survey during 1977-1978 (Marshall 1979) yields an upper limit to the quiescent flux level of ti 1 x 10 -11 erg cm 2 s -1 (2-10 keV), implying a variability of ti 5 x 104 0 Cen X-4 is also an X-ray burst source, as evident from observations of an intense Type I burst during the decline of the present outburst (Oda 1979b; Matsuoka et al. 1980) and an unusually lonq and bright burst-like event prior to the 1969 episode (Belian, Conner, and Evans 1972). UBV observations conducted approximately one week after onset of the 1979 outburst revealed the presence of a star which had brightened by at least six magnitudes over the level observed in the Palomar Observatory Sky Survey (m v ti 19; Canizares, McClintock, and Grindlay 1979a,b) at a position consistent with the revised Vela 5 X-ray location (Terrell et al. 1979). The abject was also observed during outburst at UV wavelengths with the IUE satellite (Wu 1979) and in the radio band with the Very Large Array (Hjellming 1979). In Section II we present the All-Sky Monitor observations of the 1979 episode, including evidence for a source modulation at a period of 8.2 hours, In Section III, these results are discussed in the context of the other existing data on Cen X-4 and the characteristics of the "soft" transients as a class. in Section IV, we interpret the overall source observations in terms of episodic mass exchange in a relatively close, low mass binary system with mass ratio q = Mx/Mopt ti y . 1 - 3 - II. EXPERIMENTAL RESULTS The All-Sky Monitor (ASM) on Ariel 5 is a wide-field X-ray camera which provides nearly continuous coverage of Z, 3n steradians of the sky in the 3-6 keV energy band. The instrument sensitivity is ti 0.07 and . 0.12 ph cm-2 S -1 0 photon cm -2 s -1 ti 1,3 x 10-8 erg cm-2 s -1 (2-6 keV)) for half-day integrations in the fine (6e ti 2 0 ) and coarse (6e ti 100 ) spatial resolution modes, respectively. The temporal resolution is defined by the satellite orbital period of ti 100 minutes. No spectral information within the nominal 3-6 keV energy window is retained. A detailed description of the ASM is given in Holt (1976). a. Light Curve Onset of the present outburst from Cen X-4 occurred between % 1100 hrs UT on 1979 May 11 and ti 0100 hrs UT on May 13, where the uncertaint y reflects a gap in all-sky coverage resulting from fine- mode observations of the Norma-Circinus region during that interval. The source brightened rapidly from a level of . 0.8 ph cm -2 s -1 , attaining a flux of ti 5 ph cm-e s- 1 early on May 17. The phase of maximum light lasted until ti May 24, when an abrupt decline (e-folding time T \, 3 days) commenced, the flux drerping below the ASM threshold by ti June 10. ASM coverage of the Centaurus region durir;- 1974 October - 1979 April produced no significant source detections, thereby excluding (except for occasional brief gaps in coverage) outbursts of peak flux ^ 0.2 ph cm-2 s -1 during that interval.. The ASM light curve of this episode is shown in Figure 1. We note several interesting aspects of the 1979 event apparent in this Figure: (1) the light curve exhibits many of the characteristic features observed from other transients, including a pre-cursor peak (or more appropriately, a "pre-maximum halt"; see May 14), a double-peaked maximum (May 16-21), secondary maxima or plateaus during the decline phase (e.g., May 22-24, 28-30), and the absence of eclipse-like modulation; (2) the presence of significant, apparently random variations on time scales down to the limiting instrumental resolution, particularly during W. - 4 - maximum light; and (3) the lower peak flux and shorter duration relative to the 1969 event (S max (1979) ti 0,, 2 Smax 0969) ; T .01 (1979) ti 0.4 T 01 (1969) , where T O1 = time to reach 0.01 We also note the similarity of the Smax)' light curve to that of H1705-25 (Nova Ophiuchi 1977). Except for a substantial difference in the time scales of the final decay (T Ol 11. 1 month and > 5 months for Cen X-4 and H1705-25, respectively), the characteristics of the 1979 flare of Cen X-4 (including rise-time, precursor/pre-maximum halt, doub l e-peaked maximum, duration of maximum light, and rate of initial decline) are strikingly similar co those of 111705-25 (cf, Figure 1, Watson, Ricketts, and Griffiths 1978), b Periodic Behavior A search for a possible underlying periodic modulation was conducted by application of the standard epoch-folding technique to the data of Figure Linear decay trends (obtained via visual fits to the data) over the intervals corresponding to May 24-26, May 27-28, and May 29-June 2 were subtracted from the data and a d_c, component of 1„6 ph cm -2 s -1 added to the residuals. The entire decline phase data sample (May 24-June 2) was then folded in 7 bins over trial periods in the range P=0,.1 - 5 days, and the resulting x 2 distribution (vs. the assumption of source constancy) inspected for deviations above the average level„ As shown in Figure 2, a relative maximum in the ,, 2 distribution is observQd in the vicinity of P o = 0.3415d (-,, 8 2 h ), ana weaker maxima are evident at the n=2 and 3 multiples of th y,.: period. No deviation is apparent at P o/2 (0.1708d), This latter period is close to the 4 8 hour (0.1994 ) period of Cyg X-3, which is clearly dete(table with the ASM over longer intervals (but with a lower average flux; cf_ Holt et al. 1919)„ In Figure 3a, the detailed variation of x 2 near 0 3415 d is shown We note that the width of the x 2 maximum is commensurate with that expected froc, a true modulation at this period over the data interval sampled (­ 9 days) The shape of the modulation is sh,)wn ir, the folded light curve of Figure 3b, and is consistent with either a sinusoidal or "dip”-like variation - 5 - The reality of the 8.2 h effect was investigated in several ways.. The data in Figure 1 during the phase of maximum light (May 16-24) were folded in the same fashion as the decline phase data. In addition to the higher average level of X 2 , several peaks in the vicinity of 8.2 hr are evidenT gut inconsistent with this period. We do not consider this irreconcilable with the earlier result, however, primarily because of the larger short- and long-term fluctuations evident during the stage of X-ray maximum. The likely significant variation in physical conditions at the source corresponding to the peak and decay stages could also account for the differing results.
Load more

Recommended publications
  • Stsci Newsletter: 1997 Volume 014 Issue 01
    January 1997 • Volume 14, Number 1 SPACE TELESCOPE SCIENCE INSTITUTE Highlights of this issue: • AURA science and functional awards to Leitherer and Hanisch — pages 1 and 23 • Cycle 7 to be extended — page 5 • Cycle 7 approved Newsletter program listing — pages 7-13 Astronomy with HST Climbing the Starburst Distance Ladder C. Leitherer Massive stars are an important and powerful star formation events in sometimes dominant energy source for galaxies. Even the most luminous star- a galaxy. Their high luminosity, both in forming regions in our Galaxy are tiny light and mechanical energy, makes on a cosmic scale. They are not them detectable up to cosmological dominated by the properties of an distances. Stars ~100 times more entire population but by individual massive than the Sun are one million stars. Therefore stochastic effects times more luminous. Except for stars prevail. Extinction represents a severe of transient brightness, like novae and problem when a reliable census of the supernovae, hot, massive stars are Galactic high-mass star-formation the most luminous stellar objects in history is atempted, especially since the universe. massive stars belong to the extreme Massive stars are, however, Population I, with correspondingly extremely rare: The number of stars small vertical scale heights. Moreover, formed per unit mass interval is the proximity of Galactic regions — roughly proportional to the -2.35 although advantageous for detailed power of mass. We expect to find very studies of individual stars — makes it few massive stars compared to, say, difficult to obtain integrated properties, solar-type stars. This is consistent with such as total emission-line fluxes of observations in our solar neighbor- the ionized gas.
    [Show full text]
  • GU Monocerotis: a High-Mass Eclipsing Overcontact Binary in the Young Open Cluster Dolidze 25? J
    A&A 590, A45 (2016) Astronomy DOI: 10.1051/0004-6361/201628224 & c ESO 2016 Astrophysics GU Monocerotis: A high-mass eclipsing overcontact binary in the young open cluster Dolidze 25? J. Lorenzo1, I. Negueruela1, F. Vilardell2, S. Simón-Díaz3; 4, P. Pastor5, and M. Méndez Majuelos6 1 Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Escuela Politécnica Superior, Universidad de Alicante, Carretera de San Vicente del Raspeig s/n, 03690 San Vicente del Raspeig, Alicante, Spain e-mail: [email protected] 2 Institut d’Estudis Espacials de Catalunya, Edifici Nexus, c/ Capitá, 2−4, desp. 201, 08034 Barcelona, Spain 3 Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain 4 Departamento de Astrofísica, Universidad de La Laguna, Facultad de Física y Matemáticas, Avda. Astrofísico Francisco Sánchez s/n, 38205 La Laguna, Tenerife, Spain 5 Departamento de Lenguajes y Sistemas Informáticos, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain 6 Departamento de Ciencias, IES Arroyo Hondo, c/ Maestro Manuel Casal 2, 11520 Rota, Cádiz, Spain Received 30 January 2016 / Accepted 3 March 2016 ABSTRACT Context. The eclipsing binary GU Mon is located in the star-forming cluster Dolidze 25, which has the lowest metallicity measured in a Milky Way young cluster. Aims. GU Mon has been identified as a short-period eclipsing binary with two early B-type components. We set out to derive its orbital and stellar parameters. Methods. We present a comprehensive analysis, including B and V light curves and 11 high-resolution spectra, to verify the orbital period and determine parameters.
    [Show full text]
  • Uvsat: a Concept of an Ultraviolet/Optical Photometric Satellite
    UVSat: a concept of an ultraviolet/optical photometric satellite A. Pigulski1, A. Baran2, M. Bzowski3, H. Cugier1, B. Czerny4, J. Daszy´nska-Daszkiewicz1, W. Dziembowski5·6, G. Handler5, Z. Ko laczkowski1, M. Kr´olikowska3, J. Krzesi´nski2, G. Maciejewski7, G. Michalska1, J. Molenda-Zakowicz_ 1, P. Moskalik5, A. Niedzielski7, E. Niemczura1, J. Ostrowski1, A. Pamyatnykh5, M. Ratajczak1, S. Rucinski8, M. Siwak2, R. Smolec5, S. Szutowicz3, T. Tomov7,L. Wyrzykowski6, S. Zo la9 and M. Sarna5 1. Instytut Astronomiczny, Uniwersytet Wroc lawski, Kopernika 11, 51-622 Wroc law, Poland 2. Instytut Fizyki Uniwersytetu Pedagogicznego, Podchora_zych, 2, 30-084 Krak´ow, Poland 3. Centrum Bada´nKosmicznych PAN, Bartycka 18a, 00-716 Warszawa, Poland 4. Centrum Fizyki Teoretycznej PAN, Al. Lotnik´ow 32/46, 02-668 Warszawa, Poland 5. Centrum Astronomiczne im. M. Kopernika PAN, Bartycka 18, 00-716 Warszawa, Poland 6. Obserwatorium Astronomiczne Uniwersytetu Warszawskiego, Al. Ujazdowskie 4, 00-478 Warszawa, Poland 7. Centrum Astronomii, Wydzia lFizyki, Astronomii i Informatyki Stosowanej, Uniwersytet Miko laja Kopernika, Grudziadzka, 5, 87-100 Toru´n, Poland 8. Department of Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, Canada 9. Obserwatorium Astronomiczne Uniwersytetu Jagiello´nskiego, Orla 171, 30-244 Krak´ow, Poland Time-series photometry from space in the ultraviolet can be presently done with only a few platforms, none of which is able to provide wide-field long-term high- cadence photometry. We present a concept of UVSat, a twin space telescope which will be capable to perform this kind of photometry, filling an observational niche. The satellite will host two telescopes, one for observations in the ultravi- olet, the other for observations in the optical band.
    [Show full text]
  • A New Universe to Discover: a Guide to Careers in Astronomy
    A New Universe to Discover A Guide to Careers in Astronomy Published by The American Astronomical Society What are Astronomy and Astrophysics? Ever since Galileo first turned his new-fangled one-inch “spyglass” on the moon in 1609, the popular image of the astronomer has been someone who peers through a telescope at the night sky. But astronomers virtually never put eye to lens these days. The main source of astronomical data is still photons (particles of light) from space, but the tools used to gather and analyze them are now so sophisticated that it’s no longer necessary (or even possible, in most cases) for a human eye to look through them. But for all the high-tech gadgetry, the 21st-Century astronomer is still trying to answer the same fundamental questions that puzzled Galileo: How does the universe work, and where did it come from? Webster’s dictionary defines “astronomy” as “the science that deals with the material universe beyond the earth’s atmosphere.” This definition is broad enough to include great theoretical physicists like Isaac Newton, Albert Einstein, and Stephen Hawking as well as astronomers like Copernicus, Johanes Kepler, Fred Hoyle, Edwin Hubble, Carl Sagan, Vera Rubin, and Margaret Burbidge. In fact, the words “astronomy” and “astrophysics” are pretty much interchangeable these days. Whatever you call them, astronomers seek the answers to many fascinating and fundamental questions. Among them: *Is there life beyond earth? *How did the sun and the planets form? *How old are the stars? *What exactly are dark matter and dark energy? *How did the Universe begin, and how will it end? Astronomy is a physical (non-biological) science, like physics and chemistry.
    [Show full text]
  • Arxiv:0908.2624V1 [Astro-Ph.SR] 18 Aug 2009
    Astronomy & Astrophysics Review manuscript No. (will be inserted by the editor) Accurate masses and radii of normal stars: Modern results and applications G. Torres · J. Andersen · A. Gim´enez Received: date / Accepted: date Abstract This paper presents and discusses a critical compilation of accurate, fun- damental determinations of stellar masses and radii. We have identified 95 detached binary systems containing 190 stars (94 eclipsing systems, and α Centauri) that satisfy our criterion that the mass and radius of both stars be known to ±3% or better. All are non-interacting systems, so the stars should have evolved as if they were single. This sample more than doubles that of the earlier similar review by Andersen (1991), extends the mass range at both ends and, for the first time, includes an extragalactic binary. In every case, we have examined the original data and recomputed the stellar parameters with a consistent set of assumptions and physical constants. To these we add interstellar reddening, effective temperature, metal abundance, rotational velocity and apsidal motion determinations when available, and we compute a number of other physical parameters, notably luminosity and distance. These accurate physical parameters reveal the effects of stellar evolution with un- precedented clarity, and we discuss the use of the data in observational tests of stellar evolution models in some detail. Earlier findings of significant structural differences between moderately fast-rotating, mildly active stars and single stars, ascribed to the presence of strong magnetic and spot activity, are confirmed beyond doubt. We also show how the best data can be used to test prescriptions for the subtle interplay be- tween convection, diffusion, and other non-classical effects in stellar models.
    [Show full text]
  • FY13 High-Level Deliverables
    National Optical Astronomy Observatory Fiscal Year Annual Report for FY 2013 (1 October 2012 – 30 September 2013) Submitted to the National Science Foundation Pursuant to Cooperative Support Agreement No. AST-0950945 13 December 2013 Revised 18 September 2014 Contents NOAO MISSION PROFILE .................................................................................................... 1 1 EXECUTIVE SUMMARY ................................................................................................ 2 2 NOAO ACCOMPLISHMENTS ....................................................................................... 4 2.1 Achievements ..................................................................................................... 4 2.2 Status of Vision and Goals ................................................................................. 5 2.2.1 Status of FY13 High-Level Deliverables ............................................ 5 2.2.2 FY13 Planned vs. Actual Spending and Revenues .............................. 8 2.3 Challenges and Their Impacts ............................................................................ 9 3 SCIENTIFIC ACTIVITIES AND FINDINGS .............................................................. 11 3.1 Cerro Tololo Inter-American Observatory ....................................................... 11 3.2 Kitt Peak National Observatory ....................................................................... 14 3.3 Gemini Observatory ........................................................................................
    [Show full text]
  • GEORGE HERBIG and Early Stellar Evolution
    GEORGE HERBIG and Early Stellar Evolution Bo Reipurth Institute for Astronomy Special Publications No. 1 George Herbig in 1960 —————————————————————– GEORGE HERBIG and Early Stellar Evolution —————————————————————– Bo Reipurth Institute for Astronomy University of Hawaii at Manoa 640 North Aohoku Place Hilo, HI 96720 USA . Dedicated to Hannelore Herbig c 2016 by Bo Reipurth Version 1.0 – April 19, 2016 Cover Image: The HH 24 complex in the Lynds 1630 cloud in Orion was discov- ered by Herbig and Kuhi in 1963. This near-infrared HST image shows several collimated Herbig-Haro jets emanating from an embedded multiple system of T Tauri stars. Courtesy Space Telescope Science Institute. This book can be referenced as follows: Reipurth, B. 2016, http://ifa.hawaii.edu/SP1 i FOREWORD I first learned about George Herbig’s work when I was a teenager. I grew up in Denmark in the 1950s, a time when Europe was healing the wounds after the ravages of the Second World War. Already at the age of 7 I had fallen in love with astronomy, but information was very hard to come by in those days, so I scraped together what I could, mainly relying on the local library. At some point I was introduced to the magazine Sky and Telescope, and soon invested my pocket money in a subscription. Every month I would sit at our dining room table with a dictionary and work my way through the latest issue. In one issue I read about Herbig-Haro objects, and I was completely mesmerized that these objects could be signposts of the formation of stars, and I dreamt about some day being able to contribute to this field of study.
    [Show full text]
  • Astronomy 2009 Index
    Astronomy Magazine 2009 Index Subject Index 1RXS J160929.1-210524 (star), 1:24 4C 60.07 (galaxy pair), 2:24 6dFGS (Six Degree Field Galaxy Survey), 8:18 21-centimeter (neutral hydrogen) tomography, 12:10 93 Minerva (asteroid), 12:18 2008 TC3 (asteroid), 1:24 2009 FH (asteroid), 7:19 A Abell 21 (Medusa Nebula), 3:70 Abell 1656 (Coma galaxy cluster), 3:8–9, 6:16 Allen Telescope Array (ATA) radio telescope, 12:10 ALMA (Atacama Large Millimeter/sub-millimeter Array), 4:21, 9:19 Alpha (α) Canis Majoris (Sirius) (star), 2:68, 10:77 Alpha (α) Orionis (star). See Betelgeuse (Alpha [α] Orionis) (star) Alpha Centauri (star), 2:78 amateur astronomy, 10:18, 11:48–53, 12:19, 56 Andromeda Galaxy (M31) merging with Milky Way, 3:51 midpoint between Milky Way Galaxy and, 1:62–63 ultraviolet images of, 12:22 Antarctic Neumayer Station III, 6:19 Anthe (moon of Saturn), 1:21 Aperture Spherical Telescope (FAST), 4:24 APEX (Atacama Pathfinder Experiment) radio telescope, 3:19 Apollo missions, 8:19 AR11005 (sunspot group), 11:79 Arches Cluster, 10:22 Ares launch system, 1:37, 3:19, 9:19 Ariane 5 rocket, 4:21 Arianespace SA, 4:21 Armstrong, Neil A., 2:20 Arp 147 (galaxy pair), 2:20 Arp 194 (galaxy group), 8:21 art, cosmology-inspired, 5:10 ASPERA (Astroparticle European Research Area), 1:26 asteroids. See also names of specific asteroids binary, 1:32–33 close approach to Earth, 6:22, 7:19 collision with Jupiter, 11:20 collisions with Earth, 1:24 composition of, 10:55 discovery of, 5:21 effect of environment on surface of, 8:22 measuring distant, 6:23 moons orbiting,
    [Show full text]
  • The Evolution of Hierarchical Triple Star-Systems
    Toonen et al. Computational Astrophysics and Cosmology (2016)3:6 DOI 10.1186/s40668-016-0019-0 METHODOLOGY OpenAccess The evolution of hierarchical triple star-systems Silvia Toonen* , Adrian Hamers and Simon Portegies Zwart Abstract Field stars are frequently formed in pairs, and many of these binaries are part of triples or even higher-order systems. Even though, the principles of single stellar evolution and binary evolution, have been accepted for a long time, the long-term evolution of stellar triples is poorly understood. The presence of a third star in an orbit around a binary system can significantly alter the evolution of those stars and the binary system. The rich dynamical behaviour in three-body systems can give rise to Lidov-Kozai cycles, in which the eccentricity of the inner orbit and the inclination between the inner and outer orbit vary periodically. In turn, this can lead to an enhancement of tidal effects (tidal friction), gravitational-wave emission and stellar interactions such as mass transfer and collisions. The lack of a self-consistent treatment of triple evolution, including both three-body dynamics as well as stellar evolution, hinders the systematic study and general understanding of the long-term evolution of triple systems. In this paper, we aim to address some of these hiatus, by discussing the dominant physical processes of hierarchical triple evolution, and presenting heuristic recipes for these processes. To improve our understanding on hierarchical stellar triples, these descriptions are implemented in a public source code TrES, which combines three-body dynamics (based on the secular approach) with stellar evolution and their mutual influences.
    [Show full text]
  • Science Cases for a Visible Interferometer
    March 22, 2017 0:30 World Scientific Book - 9.75in x 6.5in Science_cases_visible page i September, 29 2015 Science cases for a visible interferometer arXiv:1703.02395v3 [astro-ph.SR] 21 Mar 2017 Publishers' page i March 22, 2017 0:30 World Scientific Book - 9.75in x 6.5in Science_cases_visible page ii Publishers' page ii March 22, 2017 0:30 World Scientific Book - 9.75in x 6.5in Science_cases_visible page iii Publishers' page iii March 22, 2017 0:30 World Scientific Book - 9.75in x 6.5in Science_cases_visible page iv Publishers' page iv March 22, 2017 0:30 World Scientific Book - 9.75in x 6.5in Science_cases_visible page v This book is dedicated to the memory of our colleague Olivier Chesneau who passed away at the age of 41. v March 22, 2017 0:30 World Scientific Book - 9.75in x 6.5in Science_cases_visible page vi vi Science cases for a visible interferometer March 22, 2017 0:30 World Scientific Book - 9.75in x 6.5in Science_cases_visible page vii Preface High spatial resolution is the key for the understanding of various astrophysical phenomena. But even with the future E-ELT, single dish instrument are limited to a spatial resolution of about 4 mas in the visible whereas, for the closest objects within our Galaxy, most of the stellar photosphere remain smaller than 1 mas. Part of these limitations was the success of long baseline interferometry with the AMBER (Petrov et al., 2007) instrument on the VLTI, operating in the near infrared (K band) of the MIDI instrument (Leinert et al., 2003) in the thermal infrared (N band).
    [Show full text]
  • How Astronomical Objects Are Named
    How Astronomical Objects Are Named Jeanne E. Bishop Westlake Schools Planetarium 24525 Hilliard Road Westlake, Ohio 44145 U.S.A. bishop{at}@wlake.org Sept 2004 Introduction “What, I wonder, would the science of astrono- use of the sky by the societies of At the 1988 meeting in Rich- my be like, if we could not properly discrimi- the people that developed them. However, these different systems mond, Virginia, the Inter- nate among the stars themselves. Without the national Planetarium Society are beyond the scope of this arti- (IPS) released a statement ex- use of unique names, all observatories, both cle; the discussion will be limited plaining and opposing the sell- ancient and modern, would be useful to to the system of constellations ing of star names by private nobody, and the books describing these things used currently by astronomers in business groups. In this state- all countries. As we shall see, the ment I reviewed the official would seem to us to be more like enigmas history of the official constella- methods by which stars are rather than descriptions and explanations.” tions includes contributions and named. Later, at the IPS Exec- – Johannes Hevelius, 1611-1687 innovations of people from utive Council Meeting in 2000, many cultures and countries. there was a positive response to The IAU recognizes 88 constel- the suggestion that as continuing Chair of with the name registered in an ‘important’ lations, all originating in ancient times or the Committee for Astronomical Accuracy, I book “… is a scam. Astronomers don’t recog- during the European age of exploration and prepare a reference article that describes not nize those names.
    [Show full text]
  • Massive Stars: Life and Death
    Massive Stars: Life and Death Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Jos´eLuis Prieto Katunari´c Graduate Program in Astronomy The Ohio State University 2009 Dissertation Committee: Professor Krzysztof Z. Stanek, Advisor Professor Christopher S. Kochanek Professor John F. Beacom Copyright by Jos´eL. Prieto 2009 ABSTRACT Although small in number, massive stars are critical to the formation and evolution of galaxies. They shape the interstellar medium of galaxies through their strong winds and ultra-violet radiation, are a major source of the heavy elements enriching the interstellar medium, and are the progenitors of core-collapse supernovae and gamma-ray bursts, which are among the most energetic explosions in the Universe and mark the death of a massive star. Still, our understanding of the connection between massive stars and supernovae from observations is fairly limited. In this dissertation, I present new observational evidence that shows the importance of metallicity, mass-loss, and binarity in the lives and deaths of massive stars. We investigate how the different types of supernovae are relatively affected by the metallicity of their host galaxy. We take advantage of the large number of spectra of star-forming galaxies obtained by the Sloan Digital Sky Survey and their overlap with supernova host galaxies. We find strong evidence that type Ib/c supernovae are occurring in higher-metallicity host galaxies than type II supernovae. We discuss various implications of our findings for understanding supernova progenitors and their host galaxies, including interesting supernovae found in low-metallicity hosts.
    [Show full text]